# Enum futures_util::future::Either

``````pub enum Either<A, B> {
Left(A),
Right(B),
}``````
Expand description

Combines two different futures, streams, or sinks having the same associated types into a single type.

This is useful when conditionally choosing between two distinct future types:

``````use futures::future::Either;

let cond = true;

let fut = if cond {
Either::Left(async move { 12 })
} else {
Either::Right(async move { 44 })
};

assert_eq!(fut.await, 12);``````

## Variants§

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### Left(A)

First branch of the type

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### Right(B)

Second branch of the type

## Implementations§

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### impl<A, B> Either<A, B>

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#### pub fn as_pin_ref(self: Pin<&Self>) -> Either<Pin<&A>, Pin<&B>> ⓘ

Convert `Pin<&Either<A, B>>` to `Either<Pin<&A>, Pin<&B>>`, pinned projections of the inner variants.

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#### pub fn as_pin_mut(self: Pin<&mut Self>) -> Either<Pin<&mut A>, Pin<&mut B>> ⓘ

Convert `Pin<&mut Either<A, B>>` to `Either<Pin<&mut A>, Pin<&mut B>>`, pinned projections of the inner variants.

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### impl<A, B, T> Either<(T, A), (T, B)>

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#### pub fn factor_first(self) -> (T, Either<A, B>)

Factor out a homogeneous type from an either of pairs.

Here, the homogeneous type is the first element of the pairs.

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### impl<A, B, T> Either<(A, T), (B, T)>

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#### pub fn factor_second(self) -> (Either<A, B>, T)

Factor out a homogeneous type from an either of pairs.

Here, the homogeneous type is the second element of the pairs.

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### impl<T> Either<T, T>

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#### pub fn into_inner(self) -> T

Extract the value of an either over two equivalent types.

## Trait Implementations§

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#### fn poll_fill_buf( self: Pin<&mut Self>, cx: &mut Context<'_>, ) -> Poll<Result<&[u8]>>

Attempt to return the contents of the internal buffer, filling it with more data from the inner reader if it is empty. Read more
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#### fn consume(self: Pin<&mut Self>, amt: usize)

Tells this buffer that `amt` bytes have been consumed from the buffer, so they should no longer be returned in calls to `poll_read`. Read more
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#### fn poll_read( self: Pin<&mut Self>, cx: &mut Context<'_>, buf: &mut [u8], ) -> Poll<Result<usize>>

Attempt to read from the `AsyncRead` into `buf`. Read more
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#### fn poll_read_vectored( self: Pin<&mut Self>, cx: &mut Context<'_>, bufs: &mut [IoSliceMut<'_>], ) -> Poll<Result<usize>>

Attempt to read from the `AsyncRead` into `bufs` using vectored IO operations. Read more
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### impl<A, B> AsyncSeek for Either<A, B>where A: AsyncSeek, B: AsyncSeek,

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#### fn poll_seek( self: Pin<&mut Self>, cx: &mut Context<'_>, pos: SeekFrom, ) -> Poll<Result<u64>>

Attempt to seek to an offset, in bytes, in a stream. Read more
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### impl<A, B> AsyncWrite for Either<A, B>where A: AsyncWrite, B: AsyncWrite,

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#### fn poll_write( self: Pin<&mut Self>, cx: &mut Context<'_>, buf: &[u8], ) -> Poll<Result<usize>>

Attempt to write bytes from `buf` into the object. Read more
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#### fn poll_write_vectored( self: Pin<&mut Self>, cx: &mut Context<'_>, bufs: &[IoSlice<'_>], ) -> Poll<Result<usize>>

Attempt to write bytes from `bufs` into the object using vectored IO operations. Read more
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#### fn poll_flush(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Result<()>>

Attempt to flush the object, ensuring that any buffered data reach their destination. Read more
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#### fn poll_close(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Result<()>>

Attempt to close the object. Read more
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### impl<A: Clone, B: Clone> Clone for Either<A, B>

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#### fn clone(&self) -> Either<A, B> ⓘ

Returns a copy of the value. Read more
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#### fn clone_from(&mut self, source: &Self)

Performs copy-assignment from `source`. Read more
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### impl<A: Debug, B: Debug> Debug for Either<A, B>

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#### fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter. Read more
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### impl<A, B> FusedFuture for Either<A, B>where A: FusedFuture, B: FusedFuture<Output = A::Output>,

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#### fn is_terminated(&self) -> bool

Returns `true` if the underlying future should no longer be polled.
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### impl<A, B> FusedStream for Either<A, B>where A: FusedStream, B: FusedStream<Item = A::Item>,

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#### fn is_terminated(&self) -> bool

Returns `true` if the stream should no longer be polled.
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### impl<A, B> Future for Either<A, B>where A: Future, B: Future<Output = A::Output>,

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#### type Output = <A as Future>::Output

The type of value produced on completion.
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#### fn poll(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Self::Output>

Attempt to resolve the future to a final value, registering the current task for wakeup if the value is not yet available. Read more
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### impl<A, B, Item> Sink<Item> for Either<A, B>where A: Sink<Item>, B: Sink<Item, Error = A::Error>,

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#### type Error = <A as Sink<Item>>::Error

The type of value produced by the sink when an error occurs.
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#### fn poll_ready( self: Pin<&mut Self>, cx: &mut Context<'_>, ) -> Poll<Result<(), Self::Error>>

Attempts to prepare the `Sink` to receive a value. Read more
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#### fn start_send(self: Pin<&mut Self>, item: Item) -> Result<(), Self::Error>

Begin the process of sending a value to the sink. Each call to this function must be preceded by a successful call to `poll_ready` which returned `Poll::Ready(Ok(()))`. Read more
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#### fn poll_flush( self: Pin<&mut Self>, cx: &mut Context<'_>, ) -> Poll<Result<(), Self::Error>>

Flush any remaining output from this sink. Read more
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#### fn poll_close( self: Pin<&mut Self>, cx: &mut Context<'_>, ) -> Poll<Result<(), Self::Error>>

Flush any remaining output and close this sink, if necessary. Read more
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### impl<A, B> Stream for Either<A, B>where A: Stream, B: Stream<Item = A::Item>,

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#### type Item = <A as Stream>::Item

Values yielded by the stream.
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#### fn poll_next( self: Pin<&mut Self>, cx: &mut Context<'_>, ) -> Poll<Option<Self::Item>>

Attempt to pull out the next value of this stream, registering the current task for wakeup if the value is not yet available, and returning `None` if the stream is exhausted. Read more
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#### fn size_hint(&self) -> (usize, Option<usize>)

Returns the bounds on the remaining length of the stream. Read more

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## Blanket Implementations§

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### impl<T> Any for Twhere T: 'static + ?Sized,

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#### fn type_id(&self) -> TypeId

Gets the `TypeId` of `self`. Read more
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#### fn fill_buf(&mut self) -> FillBuf<'_, Self> ⓘwhere Self: Unpin,

Creates a future which will wait for a non-empty buffer to be available from this I/O object or EOF to be reached. Read more
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#### fn read_until<'a>( &'a mut self, byte: u8, buf: &'a mut Vec<u8>, ) -> ReadUntil<'a, Self> ⓘwhere Self: Unpin,

Creates a future which will read all the bytes associated with this I/O object into `buf` until the delimiter `byte` or EOF is reached. This method is the async equivalent to `BufRead::read_until`. Read more
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#### fn read_line<'a>(&'a mut self, buf: &'a mut String) -> ReadLine<'a, Self> ⓘwhere Self: Unpin,

Creates a future which will read all the bytes associated with this I/O object into `buf` until a newline (the 0xA byte) or EOF is reached, This method is the async equivalent to `BufRead::read_line`. Read more
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#### fn lines(self) -> Lines<Self>where Self: Sized,

Returns a stream over the lines of this reader. This method is the async equivalent to `BufRead::lines`. Read more
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#### fn chain<R>(self, next: R) -> Chain<Self, R>where Self: Sized, R: AsyncRead,

Creates an adaptor which will chain this stream with another. Read more
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#### fn read<'a>(&'a mut self, buf: &'a mut [u8]) -> Read<'a, Self> ⓘwhere Self: Unpin,

Tries to read some bytes directly into the given `buf` in asynchronous manner, returning a future type. Read more
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#### fn read_vectored<'a>( &'a mut self, bufs: &'a mut [IoSliceMut<'a>], ) -> ReadVectored<'a, Self> ⓘwhere Self: Unpin,

Creates a future which will read from the `AsyncRead` into `bufs` using vectored IO operations. Read more
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#### fn read_exact<'a>(&'a mut self, buf: &'a mut [u8]) -> ReadExact<'a, Self> ⓘwhere Self: Unpin,

Creates a future which will read exactly enough bytes to fill `buf`, returning an error if end of file (EOF) is hit sooner. Read more
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#### fn read_to_end<'a>(&'a mut self, buf: &'a mut Vec<u8>) -> ReadToEnd<'a, Self> ⓘwhere Self: Unpin,

Creates a future which will read all the bytes from this `AsyncRead`. Read more
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#### fn read_to_string<'a>( &'a mut self, buf: &'a mut String, ) -> ReadToString<'a, Self> ⓘwhere Self: Unpin,

Creates a future which will read all the bytes from this `AsyncRead`. Read more
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#### fn split(self) -> (ReadHalf<Self>, WriteHalf<Self>)where Self: AsyncWrite + Sized,

Helper method for splitting this read/write object into two halves. Read more
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#### fn take(self, limit: u64) -> Take<Self>where Self: Sized,

Creates an AsyncRead adapter which will read at most `limit` bytes from the underlying reader. Read more
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### impl<S> AsyncSeekExt for Swhere S: AsyncSeek + ?Sized,

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#### fn seek(&mut self, pos: SeekFrom) -> Seek<'_, Self> ⓘwhere Self: Unpin,

Creates a future which will seek an IO object, and then yield the new position in the object and the object itself. Read more
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#### fn stream_position(&mut self) -> Seek<'_, Self> ⓘwhere Self: Unpin,

Creates a future which will return the current seek position from the start of the stream. Read more
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### impl<W> AsyncWriteExt for Wwhere W: AsyncWrite + ?Sized,

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#### fn flush(&mut self) -> Flush<'_, Self> ⓘwhere Self: Unpin,

Creates a future which will entirely flush this `AsyncWrite`. Read more
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#### fn close(&mut self) -> Close<'_, Self> ⓘwhere Self: Unpin,

Creates a future which will entirely close this `AsyncWrite`.
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#### fn write<'a>(&'a mut self, buf: &'a [u8]) -> Write<'a, Self> ⓘwhere Self: Unpin,

Creates a future which will write bytes from `buf` into the object. Read more
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#### fn write_vectored<'a>( &'a mut self, bufs: &'a [IoSlice<'a>], ) -> WriteVectored<'a, Self> ⓘwhere Self: Unpin,

Creates a future which will write bytes from `bufs` into the object using vectored IO operations. Read more
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#### fn write_all<'a>(&'a mut self, buf: &'a [u8]) -> WriteAll<'a, Self> ⓘwhere Self: Unpin,

Write data into this object. Read more
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#### fn into_sink<Item: AsRef<[u8]>>(self) -> IntoSink<Self, Item>where Self: Sized,

Allow using an `AsyncWrite` as a `Sink``<Item: AsRef<[u8]>>`. Read more
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### impl<T> Borrow<T> for Twhere T: ?Sized,

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#### fn borrow(&self) -> &T

Immutably borrows from an owned value. Read more
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### impl<T> BorrowMut<T> for Twhere T: ?Sized,

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#### fn borrow_mut(&mut self) -> &mut T

Mutably borrows from an owned value. Read more
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### impl<T> CloneToUninit for Twhere T: Clone,

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#### default unsafe fn clone_to_uninit(&self, dst: *mut T)

🔬This is a nightly-only experimental API. (`clone_to_uninit`)
Performs copy-assignment from `self` to `dst`. Read more
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### impl<T> From<T> for T

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#### fn from(t: T) -> T

Returns the argument unchanged.

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### impl<T> FutureExt for Twhere T: Future + ?Sized,

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#### fn map<U, F>(self, f: F) -> Map<Self, F> ⓘwhere F: FnOnce(Self::Output) -> U, Self: Sized,

Map this future’s output to a different type, returning a new future of the resulting type. Read more
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#### fn map_into<U>(self) -> MapInto<Self, U> ⓘwhere Self::Output: Into<U>, Self: Sized,

Map this future’s output to a different type, returning a new future of the resulting type. Read more
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#### fn then<Fut, F>(self, f: F) -> Then<Self, Fut, F> ⓘwhere F: FnOnce(Self::Output) -> Fut, Fut: Future, Self: Sized,

Chain on a computation for when a future finished, passing the result of the future to the provided closure `f`. Read more
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#### fn left_future<B>(self) -> Either<Self, B> ⓘwhere B: Future<Output = Self::Output>, Self: Sized,

Wrap this future in an `Either` future, making it the left-hand variant of that `Either`. Read more
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#### fn right_future<A>(self) -> Either<A, Self> ⓘwhere A: Future<Output = Self::Output>, Self: Sized,

Wrap this future in an `Either` future, making it the right-hand variant of that `Either`. Read more
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#### fn into_stream(self) -> IntoStream<Self>where Self: Sized,

Convert this future into a single element stream. Read more
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#### fn flatten(self) -> Flatten<Self> ⓘwhere Self::Output: Future, Self: Sized,

Flatten the execution of this future when the output of this future is itself another future. Read more
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#### fn flatten_stream(self) -> FlattenStream<Self>where Self::Output: Stream, Self: Sized,

Flatten the execution of this future when the successful result of this future is a stream. Read more
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#### fn fuse(self) -> Fuse<Self> ⓘwhere Self: Sized,

Fuse a future such that `poll` will never again be called once it has completed. This method can be used to turn any `Future` into a `FusedFuture`. Read more
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#### fn inspect<F>(self, f: F) -> Inspect<Self, F> ⓘwhere F: FnOnce(&Self::Output), Self: Sized,

Do something with the output of a future before passing it on. Read more
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#### fn catch_unwind(self) -> CatchUnwind<Self> ⓘwhere Self: Sized + UnwindSafe,

Catches unwinding panics while polling the future. Read more
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#### fn shared(self) -> Shared<Self> ⓘwhere Self: Sized, Self::Output: Clone,

Create a cloneable handle to this future where all handles will resolve to the same result. Read more
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#### fn remote_handle(self) -> (Remote<Self>, RemoteHandle<Self::Output>)where Self: Sized,

Turn this future into a future that yields `()` on completion and sends its output to another future on a separate task. Read more
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#### fn boxed<'a>(self) -> BoxFuture<'a, Self::Output>where Self: Sized + Send + 'a,

Wrap the future in a Box, pinning it. Read more
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#### fn boxed_local<'a>(self) -> LocalBoxFuture<'a, Self::Output>where Self: Sized + 'a,

Wrap the future in a Box, pinning it. Read more
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#### fn poll_unpin(&mut self, cx: &mut Context<'_>) -> Poll<Self::Output>where Self: Unpin,

A convenience for calling `Future::poll` on `Unpin` future types.
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#### fn now_or_never(self) -> Option<Self::Output>where Self: Sized,

Evaluates and consumes the future, returning the resulting output if the future is ready after the first call to `Future::poll`. Read more
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### impl<T, U> Into<U> for Twhere U: From<T>,

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#### fn into(self) -> U

Calls `U::from(self)`.

That is, this conversion is whatever the implementation of `From<T> for U` chooses to do.

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### impl<F> IntoFuture for Fwhere F: Future,

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#### type Output = <F as Future>::Output

The output that the future will produce on completion.
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#### type IntoFuture = F

Which kind of future are we turning this into?
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#### fn into_future(self) -> <F as IntoFuture>::IntoFuture

Creates a future from a value. Read more
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### impl<T, Item> SinkExt<Item> for Twhere T: Sink<Item> + ?Sized,

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#### fn with<U, Fut, F, E>(self, f: F) -> With<Self, Item, U, Fut, F>where F: FnMut(U) -> Fut, Fut: Future<Output = Result<Item, E>>, E: From<Self::Error>, Self: Sized,

Composes a function in front of the sink. Read more
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#### fn with_flat_map<U, St, F>(self, f: F) -> WithFlatMap<Self, Item, U, St, F>where F: FnMut(U) -> St, St: Stream<Item = Result<Item, Self::Error>>, Self: Sized,

Composes a function in front of the sink. Read more
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#### fn sink_map_err<E, F>(self, f: F) -> SinkMapErr<Self, F>where F: FnOnce(Self::Error) -> E, Self: Sized,

Transforms the error returned by the sink.
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#### fn sink_err_into<E>(self) -> SinkErrInto<Self, Item, E>where Self: Sized, Self::Error: Into<E>,

Map this sink’s error to a different error type using the `Into` trait. Read more
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Close the sink.
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#### fn fanout<Si>(self, other: Si) -> Fanout<Self, Si>where Self: Sized, Item: Clone, Si: Sink<Item, Error = Self::Error>,

Fanout items to multiple sinks. Read more
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#### fn flush(&mut self) -> Flush<'_, Self, Item> ⓘwhere Self: Unpin,

Flush the sink, processing all pending items. Read more
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#### fn send(&mut self, item: Item) -> Send<'_, Self, Item> ⓘwhere Self: Unpin,

A future that completes after the given item has been fully processed into the sink, including flushing. Read more
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#### fn feed(&mut self, item: Item) -> Feed<'_, Self, Item> ⓘwhere Self: Unpin,

A future that completes after the given item has been received by the sink. Read more
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#### fn send_all<'a, St>(&'a mut self, stream: &'a mut St) -> SendAll<'a, Self, St> ⓘwhere St: TryStream<Ok = Item, Error = Self::Error> + Stream + Unpin + ?Sized, Self: Unpin,

A future that completes after the given stream has been fully processed into the sink, including flushing. Read more
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#### fn left_sink<Si2>(self) -> Either<Self, Si2> ⓘwhere Si2: Sink<Item, Error = Self::Error>, Self: Sized,

Wrap this sink in an `Either` sink, making it the left-hand variant of that `Either`. Read more
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#### fn right_sink<Si1>(self) -> Either<Si1, Self> ⓘwhere Si1: Sink<Item, Error = Self::Error>, Self: Sized,

Wrap this stream in an `Either` stream, making it the right-hand variant of that `Either`. Read more
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#### fn poll_ready_unpin( &mut self, cx: &mut Context<'_>, ) -> Poll<Result<(), Self::Error>>where Self: Unpin,

A convenience method for calling `Sink::poll_ready` on `Unpin` sink types.
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#### fn start_send_unpin(&mut self, item: Item) -> Result<(), Self::Error>where Self: Unpin,

A convenience method for calling `Sink::start_send` on `Unpin` sink types.
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#### fn poll_flush_unpin( &mut self, cx: &mut Context<'_>, ) -> Poll<Result<(), Self::Error>>where Self: Unpin,

A convenience method for calling `Sink::poll_flush` on `Unpin` sink types.
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#### fn poll_close_unpin( &mut self, cx: &mut Context<'_>, ) -> Poll<Result<(), Self::Error>>where Self: Unpin,

A convenience method for calling `Sink::poll_close` on `Unpin` sink types.
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### impl<T> StreamExt for Twhere T: Stream + ?Sized,

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#### fn next(&mut self) -> Next<'_, Self> ⓘwhere Self: Unpin,

Creates a future that resolves to the next item in the stream. Read more
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#### fn into_future(self) -> StreamFuture<Self> ⓘwhere Self: Sized + Unpin,

Converts this stream into a future of `(next_item, tail_of_stream)`. If the stream terminates, then the next item is `None`. Read more
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#### fn map<T, F>(self, f: F) -> Map<Self, F>where F: FnMut(Self::Item) -> T, Self: Sized,

Maps this stream’s items to a different type, returning a new stream of the resulting type. Read more
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#### fn enumerate(self) -> Enumerate<Self>where Self: Sized,

Creates a stream which gives the current iteration count as well as the next value. Read more
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#### fn filter<Fut, F>(self, f: F) -> Filter<Self, Fut, F>where F: FnMut(&Self::Item) -> Fut, Fut: Future<Output = bool>, Self: Sized,

Filters the values produced by this stream according to the provided asynchronous predicate. Read more
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#### fn filter_map<Fut, T, F>(self, f: F) -> FilterMap<Self, Fut, F>where F: FnMut(Self::Item) -> Fut, Fut: Future<Output = Option<T>>, Self: Sized,

Filters the values produced by this stream while simultaneously mapping them to a different type according to the provided asynchronous closure. Read more
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#### fn then<Fut, F>(self, f: F) -> Then<Self, Fut, F>where F: FnMut(Self::Item) -> Fut, Fut: Future, Self: Sized,

Computes from this stream’s items new items of a different type using an asynchronous closure. Read more
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#### fn collect<C: Default + Extend<Self::Item>>(self) -> Collect<Self, C> ⓘwhere Self: Sized,

Transforms a stream into a collection, returning a future representing the result of that computation. Read more
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#### fn unzip<A, B, FromA, FromB>(self) -> Unzip<Self, FromA, FromB> ⓘwhere FromA: Default + Extend<A>, FromB: Default + Extend<B>, Self: Sized + Stream<Item = (A, B)>,

Converts a stream of pairs into a future, which resolves to pair of containers. Read more
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#### fn concat(self) -> Concat<Self> ⓘwhere Self: Sized, Self::Item: Extend<<<Self as Stream>::Item as IntoIterator>::Item> + IntoIterator + Default,

Concatenate all items of a stream into a single extendable destination, returning a future representing the end result. Read more
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#### fn count(self) -> Count<Self> ⓘwhere Self: Sized,

Drives the stream to completion, counting the number of items. Read more
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#### fn cycle(self) -> Cycle<Self>where Self: Sized + Clone,

Repeats a stream endlessly. Read more
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#### fn fold<T, Fut, F>(self, init: T, f: F) -> Fold<Self, Fut, T, F> ⓘwhere F: FnMut(T, Self::Item) -> Fut, Fut: Future<Output = T>, Self: Sized,

Execute an accumulating asynchronous computation over a stream, collecting all the values into one final result. Read more
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#### fn any<Fut, F>(self, f: F) -> Any<Self, Fut, F> ⓘwhere F: FnMut(Self::Item) -> Fut, Fut: Future<Output = bool>, Self: Sized,

Execute predicate over asynchronous stream, and return `true` if any element in stream satisfied a predicate. Read more
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#### fn all<Fut, F>(self, f: F) -> All<Self, Fut, F> ⓘwhere F: FnMut(Self::Item) -> Fut, Fut: Future<Output = bool>, Self: Sized,

Execute predicate over asynchronous stream, and return `true` if all element in stream satisfied a predicate. Read more
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#### fn flatten(self) -> Flatten<Self>where Self::Item: Stream, Self: Sized,

Flattens a stream of streams into just one continuous stream. Read more
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#### fn flatten_unordered( self, limit: impl Into<Option<usize>>, ) -> FlattenUnordered<Self>where Self::Item: Stream + Unpin, Self: Sized,

Flattens a stream of streams into just one continuous stream. Polls inner streams produced by the base stream concurrently. Read more
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#### fn flat_map<U, F>(self, f: F) -> FlatMap<Self, U, F>where F: FnMut(Self::Item) -> U, U: Stream, Self: Sized,

Maps a stream like `StreamExt::map` but flattens nested `Stream`s. Read more
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#### fn flat_map_unordered<U, F>( self, limit: impl Into<Option<usize>>, f: F, ) -> FlatMapUnordered<Self, U, F>where U: Stream + Unpin, F: FnMut(Self::Item) -> U, Self: Sized,

Maps a stream like `StreamExt::map` but flattens nested `Stream`s and polls them concurrently, yielding items in any order, as they made available. Read more
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#### fn scan<S, B, Fut, F>(self, initial_state: S, f: F) -> Scan<Self, S, Fut, F>where F: FnMut(&mut S, Self::Item) -> Fut, Fut: Future<Output = Option<B>>, Self: Sized,

Combinator similar to `StreamExt::fold` that holds internal state and produces a new stream. Read more
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#### fn skip_while<Fut, F>(self, f: F) -> SkipWhile<Self, Fut, F>where F: FnMut(&Self::Item) -> Fut, Fut: Future<Output = bool>, Self: Sized,

Skip elements on this stream while the provided asynchronous predicate resolves to `true`. Read more
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#### fn take_while<Fut, F>(self, f: F) -> TakeWhile<Self, Fut, F>where F: FnMut(&Self::Item) -> Fut, Fut: Future<Output = bool>, Self: Sized,

Take elements from this stream while the provided asynchronous predicate resolves to `true`. Read more
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#### fn take_until<Fut>(self, fut: Fut) -> TakeUntil<Self, Fut>where Fut: Future, Self: Sized,

Take elements from this stream until the provided future resolves. Read more
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#### fn for_each<Fut, F>(self, f: F) -> ForEach<Self, Fut, F> ⓘwhere F: FnMut(Self::Item) -> Fut, Fut: Future<Output = ()>, Self: Sized,

Runs this stream to completion, executing the provided asynchronous closure for each element on the stream. Read more
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#### fn for_each_concurrent<Fut, F>( self, limit: impl Into<Option<usize>>, f: F, ) -> ForEachConcurrent<Self, Fut, F> ⓘwhere F: FnMut(Self::Item) -> Fut, Fut: Future<Output = ()>, Self: Sized,

Runs this stream to completion, executing the provided asynchronous closure for each element on the stream concurrently as elements become available. Read more
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#### fn take(self, n: usize) -> Take<Self>where Self: Sized,

Creates a new stream of at most `n` items of the underlying stream. Read more
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#### fn skip(self, n: usize) -> Skip<Self>where Self: Sized,

Creates a new stream which skips `n` items of the underlying stream. Read more
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#### fn fuse(self) -> Fuse<Self>where Self: Sized,

Fuse a stream such that `poll_next` will never again be called once it has finished. This method can be used to turn any `Stream` into a `FusedStream`. Read more
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#### fn by_ref(&mut self) -> &mut Self

Borrows a stream, rather than consuming it. Read more
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#### fn catch_unwind(self) -> CatchUnwind<Self>where Self: Sized + UnwindSafe,

Catches unwinding panics while polling the stream. Read more
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#### fn boxed<'a>(self) -> BoxStream<'a, Self::Item>where Self: Sized + Send + 'a,

Wrap the stream in a Box, pinning it. Read more
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#### fn boxed_local<'a>(self) -> LocalBoxStream<'a, Self::Item>where Self: Sized + 'a,

Wrap the stream in a Box, pinning it. Read more
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#### fn buffered(self, n: usize) -> Buffered<Self>where Self::Item: Future, Self: Sized,

An adaptor for creating a buffered list of pending futures. Read more
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#### fn buffer_unordered(self, n: usize) -> BufferUnordered<Self>where Self::Item: Future, Self: Sized,

An adaptor for creating a buffered list of pending futures (unordered). Read more
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#### fn peekable(self) -> Peekable<Self>where Self: Sized,

Creates a new stream which exposes a `peek` method. Read more
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#### fn chunks(self, capacity: usize) -> Chunks<Self>where Self: Sized,

An adaptor for chunking up items of the stream inside a vector. Read more
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#### fn forward<S>(self, sink: S) -> Forward<Self, S> ⓘwhere S: Sink<Self::Ok, Error = Self::Error>, Self: TryStream + Sized,

A future that completes after the given stream has been fully processed into the sink and the sink has been flushed and closed. Read more
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#### fn split<Item>(self) -> (SplitSink<Self, Item>, SplitStream<Self>)where Self: Sink<Item> + Sized,

Splits this `Stream + Sink` object into separate `Sink` and `Stream` objects. Read more
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#### fn inspect<F>(self, f: F) -> Inspect<Self, F>where F: FnMut(&Self::Item), Self: Sized,

Do something with each item of this stream, afterwards passing it on. Read more
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#### fn left_stream<B>(self) -> Either<Self, B> ⓘwhere B: Stream<Item = Self::Item>, Self: Sized,

Wrap this stream in an `Either` stream, making it the left-hand variant of that `Either`. Read more
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#### fn right_stream<B>(self) -> Either<B, Self> ⓘwhere B: Stream<Item = Self::Item>, Self: Sized,

Wrap this stream in an `Either` stream, making it the right-hand variant of that `Either`. Read more
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#### fn poll_next_unpin(&mut self, cx: &mut Context<'_>) -> Poll<Option<Self::Item>>where Self: Unpin,

A convenience method for calling `Stream::poll_next` on `Unpin` stream types.
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#### fn select_next_some(&mut self) -> SelectNextSome<'_, Self> ⓘwhere Self: Unpin + FusedStream,

Returns a `Future` that resolves when the next item in this stream is ready. Read more
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### impl<T> ToOwned for Twhere T: Clone,

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#### type Owned = T

The resulting type after obtaining ownership.
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#### fn to_owned(&self) -> T

Creates owned data from borrowed data, usually by cloning. Read more
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#### fn clone_into(&self, target: &mut T)

Uses borrowed data to replace owned data, usually by cloning. Read more
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### impl<T, U> TryFrom<U> for Twhere U: Into<T>,

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#### type Error = Infallible

The type returned in the event of a conversion error.
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#### fn try_from(value: U) -> Result<T, <T as TryFrom<U>>::Error>

Performs the conversion.
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### impl<F, T, E> TryFuture for Fwhere F: Future<Output = Result<T, E>> + ?Sized,

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#### type Ok = T

The type of successful values yielded by this future
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#### type Error = E

The type of failures yielded by this future
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#### fn try_poll( self: Pin<&mut F>, cx: &mut Context<'_>, ) -> Poll<<F as Future>::Output>

Poll this `TryFuture` as if it were a `Future`. Read more
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### impl<Fut> TryFutureExt for Futwhere Fut: TryFuture + ?Sized,

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#### fn flatten_sink<Item>(self) -> FlattenSink<Self, Self::Ok>where Self::Ok: Sink<Item, Error = Self::Error>, Self: Sized,

Flattens the execution of this future when the successful result of this future is a `Sink`. Read more
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#### fn map_ok<T, F>(self, f: F) -> MapOk<Self, F> ⓘwhere F: FnOnce(Self::Ok) -> T, Self: Sized,

Maps this future’s success value to a different value. Read more
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#### fn map_ok_or_else<T, E, F>(self, e: E, f: F) -> MapOkOrElse<Self, F, E> ⓘwhere F: FnOnce(Self::Ok) -> T, E: FnOnce(Self::Error) -> T, Self: Sized,

Maps this future’s success value to a different value, and permits for error handling resulting in the same type. Read more
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#### fn map_err<E, F>(self, f: F) -> MapErr<Self, F> ⓘwhere F: FnOnce(Self::Error) -> E, Self: Sized,

Maps this future’s error value to a different value. Read more
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#### fn err_into<E>(self) -> ErrInto<Self, E> ⓘwhere Self: Sized, Self::Error: Into<E>,

Maps this future’s `Error` to a new error type using the `Into` trait. Read more
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#### fn ok_into<U>(self) -> OkInto<Self, U> ⓘwhere Self: Sized, Self::Ok: Into<U>,

Maps this future’s `Ok` to a new type using the `Into` trait.
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#### fn and_then<Fut, F>(self, f: F) -> AndThen<Self, Fut, F> ⓘwhere F: FnOnce(Self::Ok) -> Fut, Fut: TryFuture<Error = Self::Error>, Self: Sized,

Executes another future after this one resolves successfully. The success value is passed to a closure to create this subsequent future. Read more
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#### fn or_else<Fut, F>(self, f: F) -> OrElse<Self, Fut, F> ⓘwhere F: FnOnce(Self::Error) -> Fut, Fut: TryFuture<Ok = Self::Ok>, Self: Sized,

Executes another future if this one resolves to an error. The error value is passed to a closure to create this subsequent future. Read more
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#### fn inspect_ok<F>(self, f: F) -> InspectOk<Self, F> ⓘwhere F: FnOnce(&Self::Ok), Self: Sized,

Do something with the success value of a future before passing it on. Read more
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#### fn inspect_err<F>(self, f: F) -> InspectErr<Self, F> ⓘwhere F: FnOnce(&Self::Error), Self: Sized,

Do something with the error value of a future before passing it on. Read more
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#### fn try_flatten(self) -> TryFlatten<Self, Self::Ok> ⓘwhere Self::Ok: TryFuture<Error = Self::Error>, Self: Sized,

Flatten the execution of this future when the successful result of this future is another future. Read more
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#### fn try_flatten_stream(self) -> TryFlattenStream<Self>where Self::Ok: TryStream<Error = Self::Error>, Self: Sized,

Flatten the execution of this future when the successful result of this future is a stream. Read more
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#### fn unwrap_or_else<F>(self, f: F) -> UnwrapOrElse<Self, F> ⓘwhere Self: Sized, F: FnOnce(Self::Error) -> Self::Ok,

Unwraps this future’s output, producing a future with this future’s `Ok` type as its `Output` type. Read more
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#### fn into_future(self) -> IntoFuture<Self> ⓘwhere Self: Sized,

Wraps a `TryFuture` into a type that implements `Future`. Read more
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#### fn try_poll_unpin( &mut self, cx: &mut Context<'_>, ) -> Poll<Result<Self::Ok, Self::Error>>where Self: Unpin,

A convenience method for calling `TryFuture::try_poll` on `Unpin` future types.
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### impl<T, U> TryInto<U> for Twhere U: TryFrom<T>,

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#### type Error = <U as TryFrom<T>>::Error

The type returned in the event of a conversion error.
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#### fn try_into(self) -> Result<U, <U as TryFrom<T>>::Error>

Performs the conversion.
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### impl<S, T, E> TryStream for Swhere S: Stream<Item = Result<T, E>> + ?Sized,

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#### type Ok = T

The type of successful values yielded by this future
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#### type Error = E

The type of failures yielded by this future
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#### fn try_poll_next( self: Pin<&mut S>, cx: &mut Context<'_>, ) -> Poll<Option<Result<<S as TryStream>::Ok, <S as TryStream>::Error>>>

Poll this `TryStream` as if it were a `Stream`. Read more
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### impl<S> TryStreamExt for Swhere S: TryStream + ?Sized,

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#### fn err_into<E>(self) -> ErrInto<Self, E>where Self: Sized, Self::Error: Into<E>,

Wraps the current stream in a new stream which converts the error type into the one provided. Read more
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#### fn map_ok<T, F>(self, f: F) -> MapOk<Self, F>where Self: Sized, F: FnMut(Self::Ok) -> T,

Wraps the current stream in a new stream which maps the success value using the provided closure. Read more
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#### fn map_err<E, F>(self, f: F) -> MapErr<Self, F>where Self: Sized, F: FnMut(Self::Error) -> E,

Wraps the current stream in a new stream which maps the error value using the provided closure. Read more
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#### fn and_then<Fut, F>(self, f: F) -> AndThen<Self, Fut, F>where F: FnMut(Self::Ok) -> Fut, Fut: TryFuture<Error = Self::Error>, Self: Sized,

Chain on a computation for when a value is ready, passing the successful results to the provided closure `f`. Read more
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#### fn or_else<Fut, F>(self, f: F) -> OrElse<Self, Fut, F>where F: FnMut(Self::Error) -> Fut, Fut: TryFuture<Ok = Self::Ok>, Self: Sized,

Chain on a computation for when an error happens, passing the erroneous result to the provided closure `f`. Read more
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#### fn inspect_ok<F>(self, f: F) -> InspectOk<Self, F>where F: FnMut(&Self::Ok), Self: Sized,

Do something with the success value of this stream, afterwards passing it on. Read more
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#### fn inspect_err<F>(self, f: F) -> InspectErr<Self, F>where F: FnMut(&Self::Error), Self: Sized,

Do something with the error value of this stream, afterwards passing it on. Read more
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#### fn into_stream(self) -> IntoStream<Self>where Self: Sized,

Wraps a `TryStream` into a type that implements `Stream` Read more
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#### fn try_next(&mut self) -> TryNext<'_, Self> ⓘwhere Self: Unpin,

Creates a future that attempts to resolve the next item in the stream. If an error is encountered before the next item, the error is returned instead. Read more
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#### fn try_for_each<Fut, F>(self, f: F) -> TryForEach<Self, Fut, F> ⓘwhere F: FnMut(Self::Ok) -> Fut, Fut: TryFuture<Ok = (), Error = Self::Error>, Self: Sized,

Attempts to run this stream to completion, executing the provided asynchronous closure for each element on the stream. Read more
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#### fn try_skip_while<Fut, F>(self, f: F) -> TrySkipWhile<Self, Fut, F>where F: FnMut(&Self::Ok) -> Fut, Fut: TryFuture<Ok = bool, Error = Self::Error>, Self: Sized,

Skip elements on this stream while the provided asynchronous predicate resolves to `true`. Read more
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#### fn try_take_while<Fut, F>(self, f: F) -> TryTakeWhile<Self, Fut, F>where F: FnMut(&Self::Ok) -> Fut, Fut: TryFuture<Ok = bool, Error = Self::Error>, Self: Sized,

Take elements on this stream while the provided asynchronous predicate resolves to `true`. Read more
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#### fn try_for_each_concurrent<Fut, F>( self, limit: impl Into<Option<usize>>, f: F, ) -> TryForEachConcurrent<Self, Fut, F> ⓘwhere F: FnMut(Self::Ok) -> Fut, Fut: Future<Output = Result<(), Self::Error>>, Self: Sized,

Attempts to run this stream to completion, executing the provided asynchronous closure for each element on the stream concurrently as elements become available, exiting as soon as an error occurs. Read more
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#### fn try_collect<C: Default + Extend<Self::Ok>>(self) -> TryCollect<Self, C> ⓘwhere Self: Sized,

Attempt to transform a stream into a collection, returning a future representing the result of that computation. Read more
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#### fn try_chunks(self, capacity: usize) -> TryChunks<Self>where Self: Sized,

An adaptor for chunking up successful items of the stream inside a vector. Read more
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#### fn try_filter<Fut, F>(self, f: F) -> TryFilter<Self, Fut, F>where Fut: Future<Output = bool>, F: FnMut(&Self::Ok) -> Fut, Self: Sized,

Attempt to filter the values produced by this stream according to the provided asynchronous closure. Read more
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#### fn try_filter_map<Fut, F, T>(self, f: F) -> TryFilterMap<Self, Fut, F>where Fut: TryFuture<Ok = Option<T>, Error = Self::Error>, F: FnMut(Self::Ok) -> Fut, Self: Sized,

Attempt to filter the values produced by this stream while simultaneously mapping them to a different type according to the provided asynchronous closure. Read more
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#### fn try_flatten_unordered( self, limit: impl Into<Option<usize>>, ) -> TryFlattenUnordered<Self>where Self::Ok: TryStream + Unpin, <Self::Ok as TryStream>::Error: From<Self::Error>, Self: Sized,

Flattens a stream of streams into just one continuous stream. Produced streams will be polled concurrently and any errors will be passed through without looking at them. If the underlying base stream returns an error, it will be immediately propagated. Read more
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#### fn try_flatten(self) -> TryFlatten<Self>where Self::Ok: TryStream, <Self::Ok as TryStream>::Error: From<Self::Error>, Self: Sized,

Flattens a stream of streams into just one continuous stream. Read more
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#### fn try_fold<T, Fut, F>(self, init: T, f: F) -> TryFold<Self, Fut, T, F> ⓘwhere F: FnMut(T, Self::Ok) -> Fut, Fut: TryFuture<Ok = T, Error = Self::Error>, Self: Sized,

Attempt to execute an accumulating asynchronous computation over a stream, collecting all the values into one final result. Read more
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#### fn try_concat(self) -> TryConcat<Self> ⓘwhere Self: Sized, Self::Ok: Extend<<<Self as TryStream>::Ok as IntoIterator>::Item> + IntoIterator + Default,

Attempt to concatenate all items of a stream into a single extendable destination, returning a future representing the end result. Read more
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#### fn try_buffer_unordered(self, n: usize) -> TryBufferUnordered<Self>where Self::Ok: TryFuture<Error = Self::Error>, Self: Sized,

Attempt to execute several futures from a stream concurrently (unordered). Read more
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#### fn try_buffered(self, n: usize) -> TryBuffered<Self>where Self::Ok: TryFuture<Error = Self::Error>, Self: Sized,

Attempt to execute several futures from a stream concurrently. Read more
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#### fn try_poll_next_unpin( &mut self, cx: &mut Context<'_>, ) -> Poll<Option<Result<Self::Ok, Self::Error>>>where Self: Unpin,

A convenience method for calling `TryStream::try_poll_next` on `Unpin` stream types.
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#### fn into_async_read(self) -> IntoAsyncRead<Self>where Self: Sized + TryStreamExt<Error = Error>, Self::Ok: AsRef<[u8]>,

Adapter that converts this stream into an `AsyncBufRead`. Read more
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#### fn try_all<Fut, F>(self, f: F) -> TryAll<Self, Fut, F> ⓘwhere Self: Sized, F: FnMut(Self::Ok) -> Fut, Fut: Future<Output = bool>,

Attempt to execute a predicate over an asynchronous stream and evaluate if all items satisfy the predicate. Exits early if an `Err` is encountered or if an `Ok` item is found that does not satisfy the predicate. Read more
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#### fn try_any<Fut, F>(self, f: F) -> TryAny<Self, Fut, F> ⓘwhere Self: Sized, F: FnMut(Self::Ok) -> Fut, Fut: Future<Output = bool>,

Attempt to execute a predicate over an asynchronous stream and evaluate if any items satisfy the predicate. Exits early if an `Err` is encountered or if an `Ok` item is found that satisfies the predicate. Read more